JP2008156551A - Glass paste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable formation of a dielectric layer etc., with a favorable surface accuracy by obtaining glass paste which shows no increase in paste viscosity, even after long-term storage, and is forming a smooth film with a uniform thickness. <P>SOLUTION: The glass paste contains a glass powder and a vehicle, provided that the chloride content in the glass paste is ≤60 ppm, preferably ≤40 ppm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a glass paste, and more particularly to a glass paste suitable for forming a dielectric layer of a plasma display panel (hereinafter referred to as PDP).

  The PDP is a self-luminous flat display panel, has excellent characteristics such as light weight and thinness, a high viewing angle, etc., and is easy to enlarge, so has attracted attention as a promising flat display device. (See Patent Documents 1 to 3).

  FIG. 1 is a schematic cross-sectional view showing the structure of the PDP. As shown in FIG. 1, a front glass substrate 1 and a rear glass substrate 2 are provided facing each other in a PDP, and a space between these glass substrates is divided into a large number of gas discharge portions. Barrier ribs) 3 are formed.

  A dielectric layer 5 is formed on the transparent electrode 4 so as to cover the entire surface of the front glass substrate 1. On the dielectric layer 5, a protective layer 6 made of MgO for stably forming plasma is formed. An address electrode 7 is formed on the rear glass substrate 2 between the partition walls 3. A dielectric layer 8 is formed on the address electrode 7 so as to cover the entire surface of the rear glass substrate 2. Further, a phosphor 9 is applied between the partition walls 3 and on the sidewalls of the partition walls 3 and the dielectric layer 8. Usually, the partition 3 is formed on the dielectric layer 8. And the panel is comprised by combining the back glass substrate 2 in which the partition 3 was formed, and the front glass substrate 1 so that it might oppose.

  In the panel structure shown in FIG. 1, the partition wall 3 is formed on the rear glass substrate 2 via the electrode protecting dielectric layer 8 covering the address electrodes 7. A panel structure that directly forms the partition 3 is also known.

  In the PDP having such a structure, when a voltage is applied between the pair of transparent electrodes 4, a plasma discharge is generated in the gas discharge portion partitioned by the partition walls 3, and ultraviolet rays generated by the plasma discharge are emitted from the phosphor 9. , And the phosphor 9 emits light, whereby an image is displayed through the front glass substrate 1.

By the way, the dielectric layer of the PDP is dried after applying a glass paste obtained by kneading and dispersing glass powder and a vehicle with a three-roll mill or the like on a glass substrate by screen printing or a slit type or roll type coater. It can be produced by firing. Generally, a vehicle is composed of a resin, a plasticizer, a solvent, and the like.
JP 2001-139342 A JP 2003-104756 A JP 2003-327448 A

  However, the conventional glass paste is kneaded and dispersed with a three-roll mill etc., and the viscosity of the paste is not stable, that is, the viscosity of the paste increases with time. It was difficult to obtain a satisfactory film thickness.

  If ethyl cellulose is used as the resin component of the vehicle, the paste viscosity can be adjusted so that a smooth and uniform film thickness can be easily obtained. Furthermore, if ethyl cellulose is used, it can be adjusted to a paste viscosity that makes it easy to obtain a smooth and uniform film thickness regardless of coating methods such as screen printing, roll coating, and slit coating. However, if ethyl cellulose is used as the resin component, the paste viscosity may increase remarkably over time, and a smooth and uniform film thickness can be obtained unless a coating operation is performed in a short period of time after producing a glass paste. It was difficult.

  Under such circumstances, it is difficult to obtain a dielectric layer with good surface accuracy in the manufacture of PDPs, etc., and particularly when a glass paste stored for a long time is used, a dielectric layer with good surface accuracy. Etc. are difficult to obtain, and this has been a cause of lowering the insulation characteristics of the dielectric layer and the like. Further, if the surface accuracy of the dielectric layer or the like deteriorates, cracks may occur on the surface of the dielectric layer or the like, and the function of the PDP may be impaired.

  Therefore, the present invention forms a dielectric layer with good surface accuracy by obtaining a glass paste that can form a smooth and uniform film thickness without unduly increasing the paste viscosity even after long-term storage. Doing this is a technical issue.

  As a result of diligent efforts, the present inventors have found that the above problems can be solved by regulating the chloride content in the glass paste to 60 ppm or less in the glass paste containing glass powder and vehicle. As suggested. The chloride content in the glass paste can be measured by the silver nitrate titration method described in JIS K2501.

  If the chloride content in the glass paste is regulated to 60 ppm or less, the paste viscosity will not unduly increase over time. The details of the mechanism of unduly increasing the paste viscosity due to chloride in the glass paste are unclear. At present, the chloride in the glass paste attracts moisture present in the glass paste due to salting out action, so that the glass component and ethyl cellulose form a strong bond, and this bond causes the viscosity of the paste over time. Is estimated to rise unjustly.

  Various methods can be adopted as a method of regulating the chloride content in the glass paste to 60 ppm or less. Among them, a method of reducing chlorides present as impurities in the vehicle as much as possible is effective. . In particular, a method for reducing the amount of chloride in the resin contained in the vehicle is effective. Methods for reducing the amount of chloride in the resin include using a high-purity resin raw material, introducing a process for removing chloride mixed in the resin manufacturing process, and washing the resin after the resin is manufactured. It is possible to adopt a thorough method. In addition, the conventional glass paste was not managed about the amount of chlorides in the glass paste, and contained about 80 to 150 ppm of chlorides.

  Secondly, the glass paste of the present invention is characterized in that the chloride content in the glass paste is 40 ppm or less.

  Thirdly, the glass paste of the present invention is characterized in that the vehicle contains ethyl cellulose and a solvent, and the chloride content in ethyl cellulose is 0.08 wt% or less. In addition, content of the chloride in ethyl cellulose can be measured by the silver nitrate titration method described in JIS K2501.

  As described above, if ethyl cellulose is used as the resin component of the vehicle, the paste viscosity may increase remarkably over time. If a glass paste is prepared and then is not applied in a short period of time, it is smooth and uniform. It was difficult to obtain a film thickness. This phenomenon is considered to be caused by the fact that the amount of chloride present in ethyl cellulose is larger than that of other resins. That is, this phenomenon is caused by the fact that NaCl in the reaction residue produced in the production process of ethyl cellulose tends to be an impurity. In general, in the production process of ethyl cellulose, there is a step of ethoxylating a hydroxyl group with chloroethane or the like, so that NaCl is easily generated as a reaction residue.

  As a method for reducing the amount of chloride in ethyl cellulose to 0.08% by weight or less, a method of thoroughly washing ethyl cellulose is effective. The amount of chloride in ethyl cellulose used in the vehicle is usually about 0.10 to 0.15% by weight, but by increasing the number of times ethyl cellulose is washed, the amount of chloride in ethyl cellulose is 0.08% by weight or less. can do. If the amount of chloride in ethyl cellulose is 0.08% by weight or less, the amount of chloride in the glass paste can be effectively reduced to 60 ppm or less.

  Therefore, in the glass paste of the present invention, if the amount of chloride in ethyl cellulose is reduced to 0.08% by weight or less, even if ethyl cellulose is used as the resin component of the vehicle, the paste viscosity is not likely to increase unduly over time. Regardless of the application method, it is easy to adjust the paste viscosity to an appropriate value for obtaining a smooth and uniform film thickness, so that the surface accuracy of the dielectric layer and the like can be remarkably improved.

  Fourth, the glass paste of the present invention is characterized in that the chloride is NaCl. Since impurities contained in ethyl cellulose are mainly NaCl, it is significant to regulate the amount of NaCl in the glass paste.

Fifth, the glass paste of the present invention is characterized in that the glass powder contains 10 to 40% by weight of B ₂ O ₃ as a glass composition.

As a result of diligent efforts, the present inventors have found that when the glass powder contains 10% by weight or more of B ₂ O ₃ as a glass composition, the paste viscosity tends to increase with time. Although the detailed mechanism of this phenomenon is not clear, when the glass powder contains 10% by weight or more of B ₂ O ₃ as a glass composition, B ₂ O ₃ is liberated into borate ions in the glass paste, and then It is presumed that borate ions form crosslinks with hydroxyl groups in the resin, and the viscosity of the paste increases remarkably over time. If an increase in paste viscosity due to free boric acid occurs in addition to an increase in paste viscosity due to chloride, these synergistic effects make it extremely difficult to obtain a smooth and uniform film thickness. In particular, when the glass paste is stored for a long period, the tendency becomes remarkable. Therefore, when the glass powder contains 10% by weight or more of B ₂ O ₃ as a glass composition, the paste viscosity tends to increase unreasonably, so the amount of chloride in the glass paste (ethyl cellulose) is regulated, and the paste viscosity The significance of suppressing the rise is greater.

  Sixth, the glass paste of the present invention is characterized by being used as a dielectric layer forming material or a partition wall forming material of a flat display device.

  Seventh, the glass paste of the present invention is characterized in that the flat display device is a PDP.

  The dielectric layer of the present invention is a dielectric layer formed on the PDP, and is characterized in that the chloride content in the dielectric layer is 100 ppm or less. The content of chloride in the dielectric layer can be measured by a silver nitrate titration method described in JIS K2501.

  The dielectric layer of the PDP is required to have good surface accuracy, for example, accuracy of ± 0.5 μm is required for a film thickness of 30 μm. In order to satisfy such surface accuracy, there is a high demand for the paste viscosity of the dielectric layer glass paste. As described above, if the glass paste of the present invention is used, a dielectric layer with high surface accuracy can be formed. However, if the amount of chloride in the glass paste is restricted to 60 ppm or less, the chlorination in the dielectric layer is performed. The content of the object is 100 ppm or less, and the surface accuracy of the dielectric layer can be increased. As a result, it is possible to improve the insulating characteristics of the dielectric layer of the PDP. Here, the dielectric layer of the PDP includes a dielectric layer that protects the transparent electrode formed on the front glass substrate and a dielectric layer that protects the address electrode formed on the rear glass substrate.

Furthermore, the dielectric layer is characterized in that the content of B ₂ O ₃ in the dielectric layer is 10 to 40% by weight.

  In the glass paste of the present invention, the amount of chloride in the glass paste is 60 ppm or less, preferably 40 ppm or less, more preferably 25 ppm or less, and still more preferably 20 ppm or less. If the amount of chloride in the glass paste exceeds 60 ppm, the paste viscosity will unduly increase over time, making it difficult to obtain a smooth and uniform film thickness. In particular, when a glass paste stored for a long time is used, the tendency becomes remarkable. In consideration of the material cost of the glass paste, it is a guideline that the amount of chloride in the glass paste is adjusted to 5 ppm or more.

  In the glass paste of the present invention, the amount of chloride in ethyl cellulose is 0.08% by weight or less, preferably 0.06% by weight or less, more preferably 0.04% by weight or less, and further preferably 0.03% by weight or less. . If the amount of chloride in the glass paste exceeds 0.08% by weight, the viscosity of the paste will unduly increase over time, making it difficult to obtain a smooth and uniform film thickness when using a glass paste stored for a long period of time. Become. In consideration of the production cost of ethyl cellulose, the amount of chloride in the glass paste is adjusted to 0.008% by weight or more.

  The glass paste of the present invention contains glass powder and a vehicle as main components. Furthermore, you may add a ceramic powder etc. to a glass paste as needed.

  Hereinafter, each component of the glass paste will be described. Needless to say, it is necessary to sufficiently manage impurities so that chlorides are not mixed in as much as possible.

  The glass powder is a component for forming a dielectric layer having a high withstand voltage and a partition wall having a practical sintering strength, and its content is 30 to 90% by weight, preferably 50 to 70% by weight. . When the content of the glass powder is less than 30% by weight, it is difficult to form a dense dielectric layer or partition. On the other hand, when the content of the glass powder is more than 90% by weight, the content of the vehicle is relatively reduced, and it is difficult to adjust the paste viscosity.

As described above, when the powder glass contains 10% by weight or more (preferably 10 to 40% by weight, more preferably 15 to 35% by weight) of B ₂ O ₃ as a glass composition, the paste is aged over time. Since the viscosity is likely to increase, the significance of reducing the amount of chloride in the glass paste (ethyl cellulose) is increased. Incidentally, the content of B ₂ O ₃ is more than 40 wt%, the glass is likely to undergo phase separation.

  Even when the glass powder contains 10% by weight or more of the total amount of alkali metal oxide and / or 15% by weight or more of the total amount of alkaline earth metal oxide as the glass composition, Since it tends to rise, the significance of regulating the amount of chloride in the glass paste (ethylcellulose) is increased.

In the glass paste of the present invention, as the glass powder, PbO—B ₂ O ₃ glass powder, ZnO—Bi ₂ O ₃ —B ₂ O ₃ glass powder, ZnO—B ₂ O ₃ —R ₂ O (R ₂ O represents Li ₂ O + Na ₂ O + K ₂ O) based glass powder is preferable because of its good thermal stability.

PbO-B ₂ O ₃ -based glass powder, a glass composition, PbO 30 to 55% by _{weight%, B 2 O 3 10~40%} , SiO 2 1~15%, 0~30% ZnO, MgO + CaO + SrO + BaO 0~30 %, Bi ₂ O ₃ 0-30%, PbO 40-50%, B ₂ O ₃ 15-35%, SiO ₂ 2-10%, ZnO 10-30%, MgO + CaO + SrO + BaO 3-20%, Bi ₂ O ₃ and more preferably contains 0-20%. If the glass composition range is regulated in this way, glass powder exhibiting good fluidity upon firing at 500 to 600 ° C. and excellent in insulating properties can be obtained.

  The reason for limiting the glass composition range as described above will be described below.

  PbO is a component that lowers the softening point, and its content is 30 to 55%, preferably 40 to 50%. If the PbO content is less than 30%, the softening point may be too high. On the other hand, if the PbO content exceeds 55%, the thermal expansion coefficient may be too high.

B ₂ O ₃ is a component that expands the vitrification range, and its content is 10 to 40%, preferably 15 to 35%. If the content of B ₂ O ₃ is less than 10%, vitrification becomes difficult. When the content of B ₂ O ₃ is more than 40%, it is not preferable because the glass tends to phase-separate.

SiO ₂ is a component that becomes a glass skeleton, and its content is 1 to 15%, preferably 2 to 10%. If the content of SiO ₂ is less than 1%, vitrification becomes difficult. If the SiO ₂ content exceeds 15%, the softening point may be too high.

  ZnO is a component that can adjust the softening point without increasing the thermal expansion coefficient, and its content is 0 to 30%, preferably 10 to 30%. When the content of ZnO exceeds 30%, the glass tends to devitrify.

  MgO, CaO, SrO and BaO are all components that enhance the thermal stability, and the total content of these components is 0 to 30%, preferably 3 to 20%. When the total amount of these components exceeds 30%, the glass composition is not balanced, and conversely, the glass tends to devitrify during firing.

Bi ₂ O ₃ is a component that lowers the softening point, and its content is 0 to 30%, preferably 0 to 20%. When the content of Bi ₂ O ₃ exceeds 30%, the thermal expansion coefficient may be too high.

  In addition to the above components, it is possible to contain other components up to 25%.

Further, PbO-B ₂ O ₃ based glass powder, the glass powder is also suitable to have a glass composition below. That is, the PbO—B ₂ O ₃ glass powder is 15% to 45% PbO, 10% to 40% B ₂ O ₃ , 1% to 15% SiO ₂ , and 0% to 10% Al ₂ O ₃ as a glass composition. ZnO 0-40%, MgO + CaO + SrO + BaO 5-30%, PbO 20-35%, B ₂ O ₃ 10-30%, SiO ₂ 2-9%, Al ₂ O ₃ 2-7%, ZnO It is more preferable to contain 15-35% and MgO + CaO + SrO + BaO 10-25%. If the glass composition range is regulated in this way, glass powder exhibiting good fluidity upon firing at 500 to 600 ° C. and excellent in insulating properties can be obtained.

  The reason for limiting the glass composition range as described above will be described below.

  PbO is a component that can lower the softening point, and its content is 15 to 45%, preferably 20 to 35%. If the PbO content is less than 15%, the softening point may be too high. On the other hand, if the content of PbO exceeds 45%, the thermal expansion coefficient may become too high.

B ₂ O ₃ is a component that expands the vitrification range, and its content is 10 to 40%, preferably 10 to 30%. If the content of B ₂ O ₃ is less than 10%, vitrification becomes difficult. On the other hand, if the content of B ₂ O ₃ is more than 40%, the glass tends to phase-separate, which is not preferable.

SiO ₂ is a component that becomes a skeleton of the glass, and its content is 1 to 15%, preferably 2 to 9%. If the content of SiO ₂ is less than 1%, vitrification becomes difficult. On the other hand, if the content of SiO ₂ exceeds 15%, the softening point may be too high.

  ZnO is a component that can adjust the softening point without increasing the thermal expansion coefficient, and its content is 0 to 40%, preferably 15 to 35%. When the content of ZnO exceeds 40%, the glass tends to devitrify.

  In addition to the above components, it is possible to contain other components up to 25%.

_{ZnO-Bi 2 O 3 -B 2} O 3 based glass powder, a glass composition, 25 to 45% ZnO by _{weight%, Bi 2 O 3 15~35%} , B 2 O 3 10~30%, SiO 2 0 ~ 8%, MgO + CaO + SrO + BaO 0 to 24% is preferable, ZnO 30 to 40%, Bi ₂ O ₃ 20 to 30%, B ₂ O ₃ 17 to 27%, SiO ₂ 3 to 7%, MgO + CaO + SrO + BaO 10 to 20 % Content is more preferable. If the glass composition range is regulated in this way, glass powder exhibiting good fluidity upon firing at 500 to 600 ° C. and excellent in insulating properties can be obtained.

  The reason for limiting the glass composition range as described above will be described below.

  ZnO is a component that lowers the thermal expansion coefficient and lowers the softening point, and its content is 25 to 45%, preferably 30 to 40%. If the ZnO content is less than 25%, the softening point may exceed 600 ° C. On the other hand, when the content of ZnO exceeds 45%, the glass tends to devitrify during firing.

Bi ₂ O ₃ is a component that lowers the softening point, and its content is 15 to 35%, preferably 20 to 30%. When the content of Bi ₂ O ₃ is less than 15%, the softening point may exceed 600 ° C. On the other hand, when the content of Bi ₂ O ₃ exceeds 35%, the glass is easily colored blackish brown.

B ₂ O ₃ is a component that expands the vitrification range, and its content is 10 to 30%, preferably 17 to 27%. If the content of B ₂ O ₃ is less than 10%, vitrification becomes difficult. On the other hand, if the content of B ₂ O ₃ is more than 30%, the glass tends to phase-separate, which is not preferable.

SiO ₂ is a skeletal component of glass, and its content is 0 to 8%, preferably 3 to 7%. If the content of SiO ₂ exceeds 8%, the softening point may exceed 600 ° C.

  MgO, CaO, SrO, and BaO are all components that increase the thermal expansion coefficient, and the total content of these components is 0 to 24%, preferably 10 to 20%. If the total amount of these components exceeds 24%, the glass tends to devitrify during firing.

  In addition to the above components, it is possible to contain other components up to 25%.

ZnO—B ₂ O ₃ —R ₂ O glass powder has a glass composition of ZnO 20 to 55%, B ₂ O ₃ 10 to 45%, K ₂ O 0 to 20%, SiO ₂ 0 to 20% by weight. %, Nb ₂ O ₅ + La ₂ O ₃ + WO ₃ 0-30%, ZnO 25-53%, B ₂ O ₃ 15-40%, K ₂ O 3-15%, Li ₂ O + Na ₂ O _{0~10%, SiO 2 3~15%,} Nb 2 O 5 + La 2 O 3 + WO 3 and more preferably contains 1% to 25%. By regulating the glass composition range in this way, it is possible to obtain a glass powder that exhibits good fluidity when fired at 500 to 600 ° C., and is less susceptible to yellowing due to reaction with Ag and Cu as electrode components. .

  The reason for limiting the glass composition range as described above will be described below.

  ZnO is a main component constituting the glass and a component that lowers the softening point, and its content is 20 to 55%, preferably 25 to 53%. When the ZnO content is less than 20%, the above effect is difficult to obtain. On the other hand, if the content of ZnO exceeds 55%, the glass tends to be crystallized, and the fluidity of the glass tends to be impaired.

B ₂ O ₃ is a component that forms a glass skeleton and expands the vitrification range, and its content is 10 to 45%, preferably 15 to 40%. When the content of B ₂ O ₃ is less than 10%, the glass is easily crystallized. On the other hand, when the content of B ₂ O ₃ is more than 45%, the softening point tends to be high, and it becomes difficult to fire at a temperature of 600 ° C. or lower. In addition, the thermal expansion coefficient tends to be larger than that of the glass substrate, making it difficult to match the thermal expansion coefficient of the glass substrate.

K ₂ O has a function of lowering the softening point and adjusting the thermal expansion coefficient, and is a component that suppresses yellowing due to reaction with Ag and Cu as electrode components, and its content is 0. -20%, preferably 3-15%. When the content of K ₂ O exceeds 20%, the thermal expansion coefficient tends to be larger than that of the glass substrate, and it becomes difficult to match the thermal expansion coefficient of the glass substrate.

SiO ₂ is a component that forms a glass skeleton, and its content is 0 to 20%, preferably 3 to 15%. When the content of SiO ₂ exceeds 20%, the softening point tends to be high, and it becomes difficult to fire at a temperature of 600 ° C. or lower.

Nb ₂ O ₅ , La ₂ O ₃ and WO ₃ are components that improve the dielectric constant and improve the insulation, and these components are 0 to 30% in total, preferably 1 to 25%, more preferably Is 3 to 20%. If the total amount of these components is more than 30%, the glass will be easily crystallized, and the softening point will be high, making it impossible to fire at a temperature of 600 ° C. or lower.

  Moreover, as a glass composition, in addition to the said component, the following components can further be contained.

Al ₂ O ₃ is a component that suppresses the phase separation of the glass and improves the weather resistance, and its content is 0 to 5%, preferably 0 to 3%. When the content of Al ₂ O ₃ is more than 5%, the softening point tends to increase, and it becomes difficult to fire at a temperature of 600 ° C. or lower.

Li ₂ O and Na ₂ O are components added to lower the melting point of the glass or adjust the thermal expansion coefficient, and these components are combined in an amount of 0 to 10%, preferably 0 to 5%. %. When the total amount of these components exceeds 10%, crystals tend to precipitate. Even if K ₂ O is used, it is difficult to prevent yellowing due to reaction with the electrode.

  CaO, SrO and BaO are components added to lower the softening point or adjust the thermal expansion coefficient, and these components are 0 to 20% in total. When the total amount of these components exceeds 20%, the thermal expansion coefficient tends to be larger than that of the glass substrate, and it becomes difficult to match the thermal expansion coefficient of the glass substrate.

In addition, in order to lower the softening point, the total amount of Cs ₂ O, Rb ₂ O, etc. is up to 10%, and in order to further suppress yellowing due to reaction with Ag and Cu, CuO, Bi ₂ TiO ₂ , ZrO ₂ , SnO ₂ in order to stabilize glass and improve water resistance and chemical resistance up to 10% in total amount of O ₃ , Sb ₂ O ₃ , CeO ₂ , MnO and the like. , Ta ₂ O ₅ , P ₂ O _{5 and the} like can be added up to 10% in total.

  The resin is a component that increases the film strength after drying and imparts flexibility, and its content is preferably in the range of 0.1 to 40% by weight, particularly 1 to 20% by weight. If the resin content is less than 0.1% by weight, the film strength after drying may decrease. On the other hand, when the resin content is more than 40% by weight, the paste viscosity becomes too high, and it takes a long time for decomposition and volatilization of the resin, leading to a decrease in production efficiency of PDP.

  Various materials can be used as the resin. In particular, ethyl cellulose is suitable for ensuring the smoothness of the film. When the dielectric layer is formed, the content of ethyl cellulose is preferably 1 to 8% by weight, particularly 3 to 7% by weight. When the partition is formed, the content of ethyl cellulose is preferably 0.5 to 5% by weight, particularly 1.5 to 3% by weight. Further, as the resin, in addition to ethyl cellulose, polybutyl methacrylate, polyvinyl butyral, polymethyl methacrylate, polyethyl methacrylate, and the like can be further added.

  The plasticizer is a component that controls the drying speed and imparts flexibility to the dry film, and the content thereof is 0 to 50% by weight, particularly 0.1 to 30% by weight, more preferably 0.1 to 20% by weight. % Is preferable. When the content of the plasticizer is more than 50% by weight, it is difficult to adjust the paste viscosity. As the plasticizer, butylbenzyl phthalate, dioctyl phthalate, diisooctyl phthalate, dicapryl phthalate, dibutyl phthalate and the like can be used, and these are used alone or in combination.

  The solvent is a component for making a paste, and the content thereof is preferably in the range of 5 to 60% by weight, particularly 20 to 50% by weight. If the solvent content is less than 5% by weight, the paste viscosity may be too high. If the content of the solvent is more than 60% by weight, the viscosity of the glass paste may be too low. As the solvent, terpineol, diethylene glycol monobutyl ether acetate, 2,2,4-trimethyl-1,3-pentadiol monoisobutyrate or the like can be used alone or in combination.

  In addition to the above components, ceramic powders such as alumina and zirconia can be added up to 10% by weight in order to adjust the fluidity, sinterability or thermal expansion coefficient of the glass paste. In order to prolong the pot life of the glass paste, a surfactant can be added up to 3% by weight. Furthermore, an antioxidant can be added up to 3% by weight in order to prevent a decrease in paste viscosity and a deterioration in resin properties.

  The glass paste of the present invention is preferably used for forming a dielectric layer or a partition of a flat display device. High surface accuracy is required for dielectric layers and barrier ribs of flat display devices. In addition, the glass paste used for these applications is required to have stable paste viscosity and long-term storage. Therefore, the glass paste of this invention can be used conveniently for these uses. Here, the flat display device includes a PDP, a field emission display, a fluorescent display tube, and the like.

  Next, a method for forming the dielectric layer will be described. First, a front glass substrate used for PDP is prepared. Next, using a screen printing method, a batch coating method, or the like, a glass paste is applied onto the front glass substrate to form a coating layer having a thickness of 30 to 100 μm. In addition, the electrode is previously formed in the front glass substrate, and application | coating of a glass paste is performed on it. Subsequently, the obtained coating layer is dried at a temperature of about 80 to 120 ° C. to obtain a dry film. Then, a dielectric layer can be formed by baking this dried film at a temperature of about 500 to 600 ° C. for about 5 to 15 minutes.

  In the dielectric layer of the present invention, the chloride content in the dielectric layer is 100 ppm or less, preferably 75 ppm or less, more preferably 60 ppm or less, and even more preferably 35 ppm or less. If the content of chloride in the dielectric layer is more than 100 ppm, the surface accuracy of the dielectric layer is likely to deteriorate, so that the insulating properties and transparency of the dielectric layer are likely to deteriorate, and the product characteristics of the PDP deteriorate. It becomes easy to do.

In the dielectric layer of the present invention, the B ₂ O ₃ content in the dielectric layer is preferably 10% by weight or more (more preferably 10 to 40% by weight, particularly preferably 15 to 35% by weight). When the content of B ₂ O ₃ in the dielectric layer is within the above range, it is possible to enjoy the effects of the present invention to the maximum as in the case of the glass paste of the present invention.

  In the dielectric layer of the present invention, the average surface roughness Ra of the dielectric layer is preferably less than 0.75 μm, more preferably 0.6 μm or less, and further preferably 0.3 μm or less. When the average surface roughness Ra of the dielectric layer is 0.75 μm or more, the electrical insulation of the dielectric layer tends to be lowered. In the dielectric layer according to the present invention, it is preferable that no crack exceeding 10 μm in depth, preferably 8 μm in depth, is observed in the dielectric layer. If there is a crack exceeding 10 μm in depth in the dielectric layer, the electrical insulation of the dielectric layer tends to decrease. In addition, the said surface characteristic is a value when it measures with a stylus type surface roughness meter.

  A method for forming the partition walls will be described. First, a rear glass substrate used for PDP is prepared. Next, using a screen printing method, a batch coating method, or the like, a glass paste is applied on the rear glass substrate to form a coating layer having a thickness of 30 to 500 μm, preferably 200 to 500 μm. Note that an electrode is formed on the rear glass substrate in advance, and further a dielectric layer is formed on the electrode, and the glass paste is applied thereon. The obtained coating layer is dried at a temperature of about 80 to 120 ° C. to obtain a dry film. Thereafter, a resist film is formed on the dry film, exposed and developed. Subsequently, after unnecessary portions are removed by a sandblasting method, baking is performed at a temperature of about 500 to 600 ° C. for about 5 to 15 minutes. In this way, a partition having a predetermined shape can be obtained.

  In the partition wall of the present invention, the chloride content in the partition wall is 60 ppm or less, preferably 50 ppm or less, more preferably 40 ppm or less, and even more preferably 30 ppm or less. If the content of chloride in the partition wall is more than 60 ppm, the surface accuracy of the partition wall is likely to deteriorate, so that defects such as chipping are likely to occur in the partition wall, and the product characteristics of the PDP are likely to deteriorate.

In the partition wall of the present invention, the content of B ₂ O ₃ in the partition wall is 5% by weight or more (more preferably 5 to 40% by weight, still more preferably 10 to 40% by weight, particularly preferably 15 to 35% by weight). It is preferable. When the content of B ₂ O ₃ in the partition wall is in the above range, it is possible to enjoy the effects of the present invention to the maximum as in the case of the glass paste of the present invention. Incidentally, B ₂ O ₃ content in the glass composition constituting the partition wall is preferably 10 to 40 wt%, more preferably 15 to 35 wt%.

  Hereinafter, the present invention will be described in detail based on examples.

<Experiment 1>
Tables 1-4 show examples (Nos. 1-3, 6-8, 11-13, 16-18) of the present invention and comparative examples (Nos. 4, 5, 9, 10, 14, 15, 19, 20).

First, glass raw materials were prepared so as to have the glass compositions shown in Tables 1 to 4, and the obtained glass batch was put into a platinum crucible and melted at 1300 ° C. for 2 hours. Next, the molten glass was poured onto a carbon plate to produce a flaky glass, and this glass was pulverized with a ball mill. Subsequently, the obtained powdery glass was classified to prepare a glass powder having an average particle diameter D ₅₀ of 2 μm.

  By mixing 65% by weight of the glass powder having the glass composition described in Tables 1 to 4 and 35% by weight of the vehicle described in Tables 1 to 4 and stirring them uniformly, kneading and dispersing with a three roll mill, Glass pastes described in Tables 1 to 4 were prepared. Note that bubbles and aggregates were not generated during the production of the glass paste.

  The chloride content in the paste was measured by a method based on JIS K2501. Similarly, the chloride content in the resin was measured by a method based on JIS K2501.

  The paste viscosity was measured using a DV-II viscometer (SC4-14 / 6R, 25 ° C.) manufactured by Brookfield. The paste viscosity was measured for “after paste preparation” (immediately after kneading and dispersing with a three-roll mill), “three days after paste preparation”, and “30 days after paste preparation”. Regarding the numerical values of paste viscosity in the table, the paste viscosity after “preparation of paste” was set to 100, and the paste viscosities of “after 3 days from paste preparation” and “after 30 days from paste preparation” were shown as relative values. Sample No. The paste viscosities 1 to 20 after “preparing the paste” were prepared to have the same value.

  The surface accuracy was evaluated as follows. First, a glass paste having a film thickness of 40 μm was formed by screen-printing a glass paste “30 days after the preparation of the paste” on a high strain point glass substrate, followed by drying and baking at 590 ° C. for 10 minutes. Next, the average surface roughness Ra (based on JIS B0603) of the obtained glass film was measured with a stylus type surface roughness meter, and the average surface roughness Ra was less than 0.75 μm as “◯”. What was 0.75 micrometer or more was made into "x".

  The crack was evaluated as follows. First, a glass paste having a film thickness of 40 μm was formed by screen-printing a glass paste “30 days after the preparation of the paste” on a high strain point glass substrate, followed by drying and baking at 590 ° C. for 10 minutes. Next, the average surface roughness Ra of the obtained glass film was measured with a stylus type surface roughness meter, and when the crack exceeding 10 μm in depth was not observed, “◯” was given, and the depth was 10 μm. The thing in which the crack which exceeds was considered as "x". Note that if the glass film having a thickness of 40 μm has a crack exceeding 10 μm, the withstand voltage is remarkably lowered, and dielectric breakdown is very likely to occur.

  As a result, in the glass pastes of Examples (Nos. 1 to 3, 6 to 8, 11 to 13, and 16 to 18), the increase in paste viscosity over time is moderated, and evaluation of surface accuracy and evaluation of cracks are performed. Both were good. On the other hand, the glass paste of the comparative examples (No. 4, 5, 9, 10, 14, 15, 19, 20) has an unreasonably increased paste viscosity over time, and the evaluation of surface accuracy and evaluation of cracks are not possible. Both were bad.

<Experiment 2>
The relationship between the chloride content in the glass paste and the paste viscosity will be further described.

  FIG. 2 is data showing the relationship between the chloride content in the glass paste and the paste viscosity. In FIG. 2, in order to eliminate the influence other than the chloride in the glass paste as much as possible, the components other than the chloride in the glass paste are restricted to the same content, and the conditions for producing the paste are the same. Regulated.

  Hereinafter, a method for producing the glass paste shown in FIG. 2 will be described.

First, a glass raw material was prepared so that the glass composition was 30% PbO, 20% B ₂ O ₃ , 5% SiO ₂ , 20% ZnO, 5% Al ₂ O ₃ , and 20% BaO by weight%. The obtained glass batch was put into a platinum crucible and melted at 1300 ° C. for 2 hours. Next, the molten glass was poured onto a carbon plate to produce a flaky glass, and this glass was pulverized with a ball mill. Subsequently, the obtained powdery glass was classified to prepare a glass powder having an average particle diameter D ₅₀ of 2 μm.

  Next, 65% by weight of the glass powder having the above glass composition and 35% by weight of the vehicle (6% by weight of ethyl cellulose, 4% by weight of dibutyl phthalate, 25% by weight of terpineol) were mixed, and both were mixed uniformly. A glass paste was prepared by kneading and dispersing with a roll mill. Note that bubbles and aggregates were not generated during the production of the glass paste.

  The chloride content in the glass paste was adjusted by adjusting the NaCl amount of ethyl cellulose as the resin. Further, the chloride content in the glass paste was measured by a method based on JIS K2501.

  The paste viscosity was measured using a Brookfield DV-II viscometer (SC4-14 / 6R, 25 ° C.) after 30 days from the preparation of the paste.

  As is clear from FIG. 2, it can be seen that the paste viscosity increases as the chloride content in the glass paste increases.

  The glass paste of the present invention is suitable for forming a dielectric layer or a partition wall of a flat display device such as a PDP, a field emission display, and a fluorescent display tube, and particularly suitable for forming a dielectric layer of a PDP.

It is a schematic sectional drawing which shows the structure of PDP. It is drawing which showed the relationship between content of the chloride in glass paste, and paste viscosity.

Explanation of symbols

1 Front glass substrate 2 Rear glass substrate 3 Bulkhead (barrier rib)
4 Transparent electrode 5 Dielectric layer (front side)
6 Protective layer 7 Address electrode 8 Dielectric layer (back side)
9 Phosphor

Claims (7)

In glass paste containing glass powder and vehicle,
A glass paste characterized in that the chloride content in the glass paste is 60 ppm or less.   The glass paste according to claim 1, wherein the chloride content in the glass paste is 40 ppm or less. The vehicle contains ethyl cellulose and a solvent,
And the glass paste of Claim 1 or 2 whose content of the chloride in ethyl cellulose is 0.08 weight% or less.   The glass paste according to any one of claims 1 to 3, wherein the chloride is NaCl. Glass powder, as a glass composition, the glass paste according to claim 1, the B ₂ O _3, characterized in that it contains 10 to 40 wt%.   6. The glass paste according to claim 1, wherein the glass paste is used as a dielectric layer forming material or a partition wall forming material of a flat display device.   The glass paste according to claim 6, wherein the flat display device is a plasma display panel.

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